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I have an early 2011 17" MacBook Pro (MacBookPro8,3). I opted for the CPU upgrade (2.3 GHz), but decided to put in the extra memory myself. I briefly checked that the Intel specifications stated that my CPU should support memory speeds at DDR3-1600, so I ordered a Kingston KHX1600C9S3K2_8GX (

Sadly, when I was booted into either OSX Lion or Windows 7 Ultimate (both 64-bit) the memory was still only running at DDR3-1333. It turns out that this particular memory module relies on something called the SPD XMP Extension. This is something the Apple BIOS/EFI doesn't support.

But people are running MacBook Pros at DDR3-1600! Even with a slightly different version ( of this memory module.

This lead me to the question of whether one could flash the SPD table and make modifications to it. Yes, you can. There are a few tools available for the job. I found SPDTool ( and Thaiphoon Burner (, where the former does not work on a MacBook Pro but the latter does.

I did succeed in grabbing the XMP timings and overwrote the standard timings. CPU-Z identifies my memory as PC3-12800H (800 MHz), which seems to be correct.

I accidentally overwrote the "lower" XMP profile, but that doesn't matter to me since the computer doesn't read XMP profiles anyway.

But now that I've got my timings flashed with the XMP profile data, I figured it would run at DDR3-1600 and show as 800 MHz in CPU-Z and 1600 MHz in OSX's System Profiler. It didn't. Somehow, it still makes the modules run at DDR3-1333.

Help me, Obi-Wans of the memory world. You're my only hope.

Screenshot of CPU-Z:

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up vote 2 down vote accepted

I solved it!

I read up about other SPD flashing attempts and found out about a "Checksum correct" function, which is available in both applications mentioned in the question. I applied the correction and rebooted. No go, it seemed.

But then I remembered something about an SMC (System Management Controller) reset that you could perform if the system was behaving weirdly related to hardware functions. I gave it a go. The procedure for a MacBook Pro, later than Early 2009, is the following:

  1. Shut down the computer.
  2. Plug the MagSafe adapter in if it's not connected
  3. On the built-in keyboard, press (left side) shift-control-option and the power button at the same time.
  4. Release all buttons at the same time after the chime.

After OSX had finished booted, I went to check in "About this Mac":

about this mac

Mission complete! I hope this will be of use for someone else wanting to unlock XMP profiles in their MacBook Pro.

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